This invention relates to a reference current circuit and a reference voltage circuit.
A conventional reference current circuit is disclosed in IEEE Journal of Solid-State Circuits, Vol. SC-22, No. 6, pp. 1139-1143, Dec. 1987.
In the manner which will later be described more in detail, the conventional reference current circuit comprises a primary pair of first and second transistors and a secondary pair of third and fourth transistors. The first transistor has a first emitter electrode connected to ground through a resistor. The second transistor has a second emitter electrode grounded and a second base electrode connected to a first base electrode of the first transistor. The third transistor has a third emitter electrode connected to a power supply terminal which is supplied with a power supply voltage from a power supply unit. The third transistor has a third collector electrode connected to a first collector electrode of the first transistor. The fourth transistor has a fourth emitter electrode connected to the power supply terminal and a fourth base electrode connected to a third base electrode of the third transistor. The fourth transistor has a fourth collector electrode connected to the fourth base electrode of the fourth transistor and a first collector electrode of the first transistor.
A fifth transistor has a fifth emitter electrode connected to the power supply terminal and a fifth electrode connected to the third collector electrode of the third transistor. A sixth transistor has a sixth emitter electrode grounded and a sixth collector electrode connected to a fifth collector electrode of the fifth transistor. The fifth transistor has a fifth base electrode connected to the sixth collector electrode of the sixth transistor and the first base electrode of the first transistor.
The first transistor has an emitter area which is Ki times as large as a unit emitter area of a unit transistor. Each of the second through the fourth transistors has an emitter area which is equal to the unit emitter area. Each of the fifth and the sixth transistors has an emitter area which is two times as large as the unit emitter area. Inasmuch as the fifth transistor has the emitter area which is two times as large as the unit emitter area of the unit transistor, a collector current of the first transistor is almost equal to a collector current of the second transistor.
However, in this conventional reference current circuit, a difference collector current is caused by Early voltage effect in response to a change of the power supply voltage. As a result, it is hardly possible in the conventional reference current circuit to prevent occurrence of the difference base emitter voltage which is caused by Early voltage effect.
It is hardly possible in the conventional reference current circuit to change the reference current circuit into a reference voltage circuit.
The conventional reference current circuit has a large amount of consumption current.